Meet with the permits department prior to closing and consult with a architect.

Whether it's extreme rehab, quick closing/cash offer because seller needs it gone, or risk due to area/permitting/market timing

My plumbing permit also expired a few weeks ago.

You need to make absolutely sure you are permitted to do this conversion with the powers that be; if not, you'll eventually get a rude surprise when a disgruntled tenant or neighbor rats you out.

As you are likely covered under the mil VA plans, I don't think you have an option to get a HDHP that permits opening/funding an HSA account.  

I own the land and have permits for a small 12-unit apartment ground up.

If it needs to be annexed and or zoned, does what you want to do with it fit the permitting authorities long range master planning?

The best opportunities are for properties in densely populated areas where cell towers are not permitted.

That includes zoning, (including a zoning letter to confirm legal use) building, permits, sales tax, licensing, etc.

Do you think there is a high-risk that an owner occupied permit could be revoked or that the city will change their regulations?